Consideration of the Role of Antigenic Keratan Sulphate Reacting to a 1/14/16H9 Antibody as a Molecular Marker to Monitor Cartilage Metabolism in Horses

Abstract

ABSTRACT. The role of keratan sulphate (KS) as a marker of cartilage metabolism was evaluated by using an in vitro model of equine articular cartilage. Articular cartilage was harvested from clinically healthy 6-month-old foals (n=3). Chondrocytes were centrifuged and cultured as pellets. Chondrocyte pellets were stimulated by insulin-like growth factor (IGF)-Iα or interleukin (IL)-1α for 2 weeks. The sulfated glycosaminoglycans (GAG) and antigenic KS concentrations in the culture media were measured by a 1,9-dimethyl-methylene blue (DMMB) colorimetric assay and an inhibition ELISA using a 1/14/16H9 antibody, respectively. Concentration of GAG was significantly increased in the media of pellets stimulated by both IGF-Iα and IL-1α. Antigenic KS concentration was significantly increased in those stimulated by IL-1α, while no significant change was found in those stimulated by IGF-Iα. A high correlation between GAG and antigenic KS concentrations was found in the media of pellets stimulated by IL-1α (r=0.87), but not in those stimulated by IGF-Iα (r=0.43). The results suggest that the concentration of antigenic KS reacting to 1/14/16H9 mirrors the GAG concentration during the stage of cartilage catabolism, but not during the cartilage anabolic stage. The concentration of antigenic KS reacting to 1/14/16H9 antibody in biological fluids could therefore be a useful marker to further understand principally the catabolic and slightly the anabolic process of articular cartilage metabolism.-KEY WORDS: cartilage metabolism, chondrocyte, equine, joint, keratan sulphate.

Serum Keratan Sulphate as a Cartilage Metabolic Marker in Horses: the Effect of Exercise

“…1). An in vitro study suggested that 1/14/16H9 antibody-reactive KS in serum and synovial fluid could contribute to the understanding of the catabolic process of articular cartilage metabolism (Okumura et al, 2000). Serum KS concentration in animals younger than 2 months of age has been found to be significantly higher than the levels in older dogs and horses (Leipold et al, 1989;Okumura et al, 1997).…”

“…Recently, an inhibition enzyme‐linked immunosorbent assay (ELISA) using a sensitive anti‐equine KS antibody 1/14/16H9 has led to improvements in the measurement of low concentrations of KS in horses (Okumura and Fujinaga, 1998). An in vitro study has suggested that 1/14/16H9 antibody‐reactive KS in serum and synovial fluid could be used as a non‐invasive cartilage metabolic marker to assist in understanding the catabolic process of articular cartilage metabolism (Okumura et al., 2000).…”